Photoluminescence from Er^(3+) ion and SnO_2 nanocrystal co-doped silica thin films

Er3＋ ions embedded in silica thin films co-doped by SnO2 nanocrystals are fabricated by sol-gel and spin coating methods. Uniformly distributed 4-am SnO2 nanocrystals are fabricated, and the nanocrystals showed tetragonal rutile crystalline structures confirmed by transmission electron microscope and X-ray diffraction measurements. A strong characteristic emission located at 1.54 〉m from the Era＋ ions is iden- tified, and the influences of Sn doping concentrations on photoluminescence properties are systematically evaluated. The emission at 1.54 #m from Era＋ ions is enhanced by more than three orders of magnitude, which can be attributed to the effective energy transfer from the defect states of SnO2 nanocrystals to nearby Er3＋ ions, as revealed by the selective excitation experiments.

Preparation and characterization of sphere-like Cu_2SnS_3 nanoparticles and their dropcasted thin films

Ternary sphere-like Cu2 SnS3（CTS）semiconductor and 2D hexagonal sheets were synthesized via a simple solvothermal method using PVP as the surface ligand at two temperatures of 180 and 220 X.The structural,morphological,and chemical compositions as well as optical properties of as-synthesized CTS particles were characterized using X-ray diffraction（XRD）,Raman spectroscopy,energy dispersive X-ray spectrometry（EDS）,field emission scanning electron microscopy（FESEM）,and UV-Vis spectroscopy.The size of sphere-like particles and the side length of hexagonal sheets were within the range of 120-140 nm and 500 nm-2 μm,respectively.FESEM,XRD,and EDS were analyzed to investigate the mechanism of the morphological evolution of CTS particles.CTS particles showed proliferation of Sn atomic ratio,which is strongly sensitive to reaction temperature and,highly affects the increase of band gap energy from 1.36 to 1.53 eV due to generation metal defects and formation SnS2-The optical analysis via the transmittance and reflectance reveals that the band-gap energy of dropcasted CTS thin films decreases after annealing due to grain growth and change of chemical compositions.Photo-responses of CTS nanocrystal thin films indicated a considerable increase in the conductivity of the films under light illumination.All these results showed the potential of these films for solar cell applications.

Preparation and characterization of Cu2ZnSn(S,Se)4 film by drop-coating of Cu2ZnSnS4 nanoink

In this work,a simple and facile one-pot oleylamine solvothermal synthetic method was developed to synthesize Cu2ZnSnS4（CZTS） nanocrystals.And the Cu2ZnSn（S,Se）4（CZTSSe） thin films were prepared by selenizing CZTS nanocrystals.The obtained CZTS nanocrystals and CZTSSe films were studied using X-ray diffraction（XRD）,transmission electron microscopy（TEM）,scanning electron microscopy（SEM）,energy-dispersive X-ray spectroscopy（EDX）,and ultraviolet–visible spectrophotometer（UV–Vis）.TEM results show that the sphere–like CZTS nanoparticles with diameter between 12 and 35 nm are polydispersed.XRD studies indicate that the prepared CZTS nanocrystals form kesterite crystal structure,and the CZTSSe films with kesterite crystal structure are also obtained at the annealing temperatures of 500 and550 °C.In particular after annealing at 500 °C for 20 min,the CZTSSe film exhibits a smooth,uniform,crack-free,and large-grained topography and possesses Cu-poor and Sn-rich composition.Moreover,it shows strong optical absorption from visible to near-infrared（IR） region,and its optical band gap（Eg） is found to be about 1.44 e V.